An Exhaust Gas Recirculation (EGR) device that recirculates a part of the exhaust gas to the intake air side is broadly used in the field of engine technology.
JP H8-49606 A discloses that the passage for the EGR gas recirculated by the EGR device is arranged in the water jacket of the cylinder head to cool the EGR gas.
JP H8-49606 A discloses that the EGR gas passage is arranged in the water jacket and the both ends of the passage are fixed to the through holes formed in the two facing walls of the water jacket of the cylinder head.
Unfortunately, the machining errors involved in the through holes may occur the misalignment between the axes of the holes. The misalignment remains the gap between the EGR gas passage and the through hole after fixing the EGR gas passage to the through holes, which occurs a problem with the fixing strength and sealing property.